Medication delivery pen assembly with needle locking safety shield

BACKGROUND OF THE INVENTION

p-0002This invention relates to needle safety devices for medication delivery pens, and more particularly, to manually-actuated safety devices for medication delivery pens.

p-0003Medication delivery pens are known in the art and are used extensively for self-administered injections, particularly with insulin. Although a medication delivery pen is normally only handled by its user, concerns exist with inadvertent skin penetration by a used pen injection needle (also referred to as a “needle stick”) particularly after disposal of a used needle.

p-0004Devices have been developed in the prior art for shielding a used medication delivery pen needle. Generally, prior art devices require complex parts and/or a multiplicity of parts. As a result, these prior art devices may not only be expensive, but may also be susceptible to failure due to their complexity. For example, U.S. Pat. No. 5,964,731, which issued on Oct. 12, 1999, discloses a manually-actuatable needle cover which includes a needle cover that is rotated through a helical track into a locked shielding position. This device, however, requires both the shielding element and an outer collar which includes the helical track. In an alternative design, as disclosed in U.S. Published patent application Ser. No. US 2002/0133122 A1, which published on Sep. 19, 2002, a normally-biased-closed shield is disclosed which is retracted upon pressing engagement against the skin of a patient. After administration, the shield locks in a protective position about the used needle. Although this device provides passive shielding without patient involvement, patients have no or poor visual contact of the needle cannula end to observe priming of the needle before use (priming of the needle is typically recommended with a small amount of liquid being expelled from the needle prior to injection to ensure that no air bubbles are entrapped within the needle).

SUMMARY OF THE INVENTION

p-0005To overcome shortcomings of the prior art, in one aspect of the subject invention, a medication delivery pen assembly is provided having a pen body and a needle assembly with a hub connected to the pen body, a needle cannula extending through the hub with a distal end sharpened for insertion into a patient, and a shield having a tubular portion telescopingly disposed about at least a portion of the hub. The tubular portion includes an internal surface, at least one projection extending inwardly from the internal surface, and the hub having at least one externally extending projection. The shield is axially displaceable relatively along the hub distally from a first position, where the distal end of the needle cannula is exposed, to a second position, where the distal end of the needle cannula is enclosed by the shield. Upon the shield being displaced to the second position, the at least one projection on the hub is deflectibly urged passed the at least one projection on the tubular portion so that subsequent distal-to-proximal movement of the shield relative to the hub is hindered by interengagement of the projections.

p-0006The subject invention is also directed to a needle assembly having a hub, a needle cannula extending through the hub with a distal end sharpened for insertion into a patient, and a shield having a tubular portion telescopingly disposed about at least a portion of the hub. The tubular portion includes an internal surface, at least one projection extending inwardly from the internal surface, and the hub having at least one externally extending projection. The shield is axially displaceable relatively along the hub distally from a first position, where the distal end of the needle cannula is exposed, to a second position, where the distal end of the needle cannula is enclosed by the shield. Upon the shield being displaced to the second position, the at least one projection on the hub is deflectibly urged passed the at least one projection on the tubular portion so that distal-to-proximal movement of the shield relative to the hub is hindered by interengagement of the projections.

p-0007The subject invention is further directed to a medication delivery pen assembly having a pen body with a needle cannula affixed thereto, the needle cannula having a distal end sharpened for insertion into a patient, a hub disposed about a portion of the needle cannula, and a shield having a tubular portion telescopingly disposed about at least a portion of the hub. The tubular portion includes an internal surface, at least one projection extending inwardly from the internal surface, and the hub having at least one externally extending projection. The shield is axially displaceable relatively along the hub distally from a first position, where the distal end of the needle cannula is exposed, to a second position, where the distal end of the needle cannula is enclosed by the shield. Upon the shield being displaced to the second position, the at least one projection on the hub is urged passed the at least one projection on the tubular portion so that distal-to-proximal movement of the shield relative to the hub is hindered by interengagement of the projections.

p-0008With the subject invention, a manually-actuatable shield is provided which is axially displaceable and that advantageously locks into a safety position enclosing a used needle. The needle assembly is preferably removable from the pen body so as to allow for needle changes, as required. The shield remains in its safety position on the needle assembly after removal and/or after disposal of the entire assembly and minimizes the chances of needle sticks occurring. As will be recognized by those skilled in the art, the subject invention can also be used in embodiments where the needle cannula is fixed to the pen body. Here, the hub can be formed unitarily with, rigidly affixed to, or removably affixed to the pen body.

p-0009As used herein, the term “proximal” and derivatives thereof, shall mean the end of an item or direction away from a patient during use of the subject invention. The term “distal”, and derivatives thereof, shall mean the end of an item or direction towards a patient during use of the subject invention.

p-0010These and other features of the invention will be better understood through a study of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0011<figref idrefs="DRAWINGS">FIG. 1</figref> is a partial exploded view of a medication delivery pen and needle assembly formed in accordance with the subject invention;

p-0012<figref idrefs="DRAWINGS">FIG. 2</figref> is a cross-sectional view of a needle assembly taken along line of <b>2</b>-<b>2</b> of <figref idrefs="DRAWINGS">FIG. 1</figref> with the shield in a retracted position and with the needle cannula exposed;

p-0013<figref idrefs="DRAWINGS">FIG. 3</figref> is a cross-sectional view of the needle assembly shown in <figref idrefs="DRAWINGS">FIG. 2</figref> with the shield in an extended position and with the needle cannula enclosed by the shield;

p-0014<figref idrefs="DRAWINGS">FIG. 4</figref> is a perspective view of the needle assembly shown in <figref idrefs="DRAWINGS">FIG. 3</figref>; and

p-0015<figref idrefs="DRAWINGS">FIG. 5</figref> is a cross-sectional view of a medication pen having a needle cannula affixed directly thereto.

DETAILED DESCRIPTION OF THE INVENTION

p-0016With reference to <figref idrefs="DRAWINGS">FIG. 1</figref>, a medication delivery pen assembly <b>10</b> is provided which generally includes a pen body <b>12</b> and a needle assembly <b>14</b>. The pen body <b>12</b> may be of any type, including that disclosed in U.S. Pat. No. 6,248,095 B1, which issued on Jun. 19, 2001, to the assignee herein. The disclosure of U.S. Pat. No. 6,248,095 B1 is incorporated herein by reference.

p-0017The pen body <b>12</b> includes a distal end <b>16</b> onto which the needle assembly <b>14</b> is removably mounted using any known technique, including threaded connections and slip connections. By way of non-limiting example, threads <b>18</b> are shown about the pen body <b>12</b> at the distal end <b>16</b>. Preferably, the needle assembly <b>14</b> is detachably mounted onto the pen body <b>12</b> to allow for removal therefrom after use, although the needle assembly <b>14</b> may be non-removably affixed to the distal end <b>16</b> where the assembly <b>10</b> does not require needle assembly replacement, such as with a single-dose unit. Optionally, a cap <b>20</b> may be provided which is formed to releasably mount onto the pen body <b>12</b>, such as with a snap or interference fit, to limit contamination of the needle assembly <b>14</b> and/or aperture <b>22</b> defined in distal end <b>16</b> of pen body <b>12</b> and which provides access into the interior of the pen body <b>12</b>. The cap may be formed in the same manner as the cap disclosed in U.S. Published patent application Ser. No. 2002/0133122 A1. U.S. Published patent application Ser. No. 2002/0133122 A1 is incorporated by reference herein in its entirety.

p-0018In a first embodiment of the subject invention, the needle assembly <b>14</b> is formed separate from the pen body <b>12</b>. As more clearly shown in <figref idrefs="DRAWINGS">FIG. 2</figref>, the needle assembly <b>14</b> includes a hub <b>24</b> with a needle shield <b>26</b> at least partially telescopingly disposed about the hub <b>24</b>. The hub <b>24</b> defines a cavity <b>27</b> with a wall <b>28</b> having a proximal end <b>30</b>; the cavity <b>27</b>, wall <b>28</b> and proximal end <b>30</b> being sized and shaped, and the wall <b>28</b> having feature(s) defined thereon, for mounting onto the distal end <b>16</b> of the pen body <b>12</b>. For example, as shown in <figref idrefs="DRAWINGS">FIG. 2</figref>, thread members <b>32</b> may be formed on an interior of the wall <b>28</b> for threaded mounting onto the threads <b>18</b> defined on pen body <b>12</b>. A needle mounting member <b>34</b> is also provided which rigidly holds a needle cannula <b>36</b>, such as, for example, with an interference fit. The needle cannula <b>36</b> may be affixed to the needle mounting member <b>34</b> using any known technique, such as with adhesive. Transverse webbing <b>38</b> connects the wall <b>28</b> and the needle mounting member <b>34</b>.

p-0019The needle cannula <b>36</b> may be of any known design and includes a sharpened distal end <b>40</b> for insertion into a patient. Preferably, proximal end <b>42</b> of the needle cannula <b>36</b> facilitates insertion into a septum of a medicinal container (not shown) that may be located inside the pen body <b>12</b>; the septum being located adjacent the aperture <b>22</b>.

p-0020The shield <b>26</b> includes a generally tubular portion <b>44</b>. In an initial state, as shown in <figref idrefs="DRAWINGS">FIG. 2</figref>, the tubular portion <b>44</b> is generally coextensive with the hub <b>24</b> and the needle cannula <b>36</b> is exposed. Preferably, a cover <b>46</b> may be provided in proximity to a distal end of the shield <b>26</b> which includes an aperture <b>48</b> formed for the passage therethrough of the needle cannula <b>36</b>. The cover <b>46</b> may prevent or restrict undesired proximal movement of the shield <b>26</b>. It is preferred that the cover <b>46</b> be formed integrally with the tubular portion <b>44</b>. By interengaging with the hub <b>24</b>, the cover <b>46</b> advantageously prevents the shield <b>26</b> from moving excessively proximally relative to the hub <b>24</b> with the shield being in its initial state as shown in <figref idrefs="DRAWINGS">FIG. 2</figref>. If the cover <b>46</b> is not provided, one or more stop members may be provided to extend inwardly from the shield <b>26</b> to engage a distal end <b>50</b> of the hub <b>24</b> and, thus, restrict proximal movement of the shield <b>26</b> relative to the hub <b>24</b>. It is also preferred that the hub <b>24</b> and the shield <b>26</b> be releasably engaged in the initial state, such as by forming a slight interference or detent fit between the two elements which may be manually overcome in displacing the shield <b>26</b> distally as described below. This limited engagement is intended to prevent inadvertent distal movement of the shield <b>26</b>. For example, distal end <b>50</b> of the hub <b>24</b> may be formed with one or more outwardly flared portions <b>52</b> which interferingly engage with the interior of the tubular portion <b>44</b>. It is preferred (but not required) that the flared portions <b>52</b> be continuous about the hub <b>24</b> in an annular shape. Alternatively, or in addition to, one or more engagement surfaces <b>25</b> may extend inwardly from the tubular portion <b>44</b> for interferingly engaging the hub <b>24</b> at its proximal end. It will be apparent from the disclosure provided herein that other structure on the hub <b>24</b> and/or shield <b>26</b> may provide the desired interference to prevent or restrict undesired movement of the shield <b>26</b> from the first position (depicted in <figref idrefs="DRAWINGS">FIG. 2</figref>).

p-0021The shield <b>26</b> is axially displaceable relative to the hub <b>24</b>, and <figref idrefs="DRAWINGS">FIGS. 3 and 4</figref> show the shield <b>26</b> being in an extended position relative to the hub <b>24</b> so as to enclose the distal end <b>40</b> of the needle cannula <b>36</b>. The tubular portion <b>44</b> has an external surface <b>45</b> which is unobstructed so as to be engagable by a user to cause relative movement between the hub <b>24</b> and the shield <b>26</b>. The external surface <b>45</b> of the tubular portion <b>44</b> may be textured or include reliefs or cut-outs to enhance the ability of a user to firmly grip and handle the shield <b>26</b>. To provide holding force to the shield <b>26</b> in the first position, it is preferred, although not required, that the flared portions <b>52</b> be formed to have an outer diameter slightly greater than the internal diameter of the shield <b>26</b> (i.e., to form an interference fit). With the hub <b>24</b> and the shield <b>26</b> being formed of a resilient material, such as thermoplastic, the flared portions <b>52</b> thus formed may resiliently press against the shield <b>26</b> and releasably hold it in the first position.

p-0022It is also preferred that the shield <b>26</b> be lockable in the extended position shown in <figref idrefs="DRAWINGS">FIGS. 3 and 4</figref>. As will be appreciated by those skilled in the art and from the disclosure provided herein, various locking mechanisms can be used. For illustrative purposes, an exemplary arrangement is depicted. One or more projections <b>54</b> extend inwardly from the interior of the shield <b>26</b>, preferably being ramped with inclined surfaces <b>56</b> that face distally and inwardly. Preferably, the projections <b>54</b> are circumferentially spaced-apart on the interior of the shield <b>26</b>. Each projection <b>54</b> has an upper surface <b>58</b> preferably disposed at an acute angle relative to the respective inclined surface <b>56</b> (i.e., an acute angle is subtended between the upper surface <b>58</b> and the inclined surface <b>56</b>). It is further preferred that the upper surfaces <b>58</b> not incline inwardly, but rather outwardly (i.e., the upper surfaces <b>58</b> preferably face proximally and outwardly, not proximally and inwardly). It is also further preferred that the upper surfaces <b>58</b> be aligned so as to collectively define a shelf (continuous or interrupted). Secondary inclined surfaces <b>57</b> may also be provided that define a greater taper leading to the inclined surfaces <b>56</b>. As such, the secondary inclined surfaces <b>57</b> allow for the projections <b>54</b> to have shorter lengths (distal to proximal) than if the inclined surfaces <b>56</b> extended directly to the tubular portion <b>44</b>.

p-0023Preferably, the flared portions <b>52</b> of the hub <b>24</b> have first and second inclined surfaces <b>60</b> and <b>62</b> that converge at the distal end <b>50</b> of the hub <b>24</b>. The first inclined surface <b>60</b> faces proximally and outwardly, while the second inclined surface <b>62</b> faces distally and inwardly. Upon displacing the shield <b>26</b> distally from its initial position to the extended position, the flared portions <b>52</b> are deflectably urged past the projections <b>54</b> formed on the shield <b>26</b>. The ramped configurations of the projections <b>54</b> and the flared portions <b>52</b> facilitate the deflection of the flared portions <b>52</b> with the first inclined surfaces <b>60</b> of the flared portions <b>52</b> riding over the inclined surfaces <b>56</b> (and secondary inclined surfaces <b>57</b>, if used) of the projections <b>54</b>. The distal end <b>50</b> is formed with a larger inner diameter than that defined between the projections <b>54</b> and, thus, once the shield <b>26</b> is in the second position (depicted in <figref idrefs="DRAWINGS">FIG. 3</figref>), movement of the shield <b>26</b> from the second position to the first position is hindered by interengagement of the flared portions <b>52</b> and the projections <b>54</b>. Additionally, the upper surfaces <b>58</b> of the projections <b>54</b> coact with the second inclined surfaces <b>62</b> of the flared portions <b>52</b> to further hinder distal-to-proximal movement with the shield <b>26</b> being in the extended position. In particular, because of the convergent shape of the distal end <b>50</b>, the distal end <b>50</b> will ride down the upper surfaces <b>58</b> upon being proximately urged; consequently, the distal end <b>50</b> will expand into a slightly enlarged state in which it is even more difficult to by-pass the projections <b>54</b> than with the distal end <b>50</b> being in its unexpanded state.

p-0024It is also preferred that one or more stop members <b>64</b> be formed at or in proximity to proximal end <b>66</b> of the shield <b>26</b> to limit distal-to-proximal movement of the shield <b>26</b> relative to the hub <b>24</b>. The stop member(s) <b>64</b> preferably each have a shoulder <b>68</b> arranged generally perpendicularly to the extended surface <b>45</b> of the tubular portion <b>44</b>. In addition, proximal ends of the first inclined surfaces <b>60</b> of the flared portions <b>52</b> preferably terminate in flat abutment surfaces <b>70</b> which are disposed generally perpendicularly to the outer wall <b>28</b> of the hub <b>24</b>. The shoulders <b>68</b> and the abutment surfaces <b>70</b> are shaped and configured for face-to-face engagement when the shield <b>26</b> is in the second position upon proximal-to-distal movement of the shield <b>26</b> relative to the hub <b>24</b>. With the annular portions <b>52</b> being nested between the projections <b>54</b> and the stop member(s) <b>64</b>, the shield <b>26</b> is locked relative to the hub <b>24</b> with movement distally or proximally being hindered. The amount of “free play” of the flared portions <b>52</b> in the locked state is a function of the spacing between the upper surfaces <b>58</b> of the projections <b>54</b> and the shoulders <b>68</b> of the stop members <b>64</b>, and is defined such that distal-to-proximal movement of the shield <b>26</b> (locked in the second position) is limited to prevent exposure of the sharpened distal end <b>40</b> of needle cannula <b>36</b>. Advantageously, the engagement surfaces <b>25</b> may be defined on the stop members <b>64</b>.

p-0025Optionally, one or more detents <b>72</b> may be provided to extend inwardly from the tubular portion <b>44</b> at locations intermediate the projections <b>54</b> and the stop members <b>64</b>. The detents <b>72</b> reduce the diameter of the tubular portion <b>44</b> and interferingly engage the flared portions <b>52</b> to generate holding force between the hub <b>24</b> and shield <b>26</b> to further limit movement of the shield <b>26</b> out of the second position. Inclined surfaces <b>74</b> may be provided to facilitate the contraction of the flared portions <b>52</b> in engaging the detents <b>72</b>.

p-0026In a second embodiment of the invention, as show in <figref idrefs="DRAWINGS">FIG. 5</figref>, the needle cannula <b>36</b> may be directly affixed to the distal end <b>16</b> of the pen body <b>12</b>. The hub <b>24</b> is located at the distal end <b>16</b> and may be formed unitarily (i.e., as one piece) with, rigidly affixed to, or removably affixed to the pen body <b>12</b> about the needle cannula <b>36</b>. <figref idrefs="DRAWINGS">FIG. 5</figref> shows the hub <b>24</b> being unitarily formed with the pen body <b>12</b>. Here, the shield <b>26</b> and the exterior of the hub <b>24</b> operate and are formed as described above.

p-0027As will be appreciated by those skilled in the art, the shield <b>26</b> is formed with sufficient length to enclose the distal end <b>40</b> of the needle cannula <b>36</b> and prevent inadvertent contact therewith when the shield <b>26</b> is in the second position. Advantageously, with the described structure, the needle assembly <b>14</b> may be removed from the pen body <b>12</b> with the shield <b>26</b> being maintained in an extended position (i.e., the second position). Moreover, the cap <b>20</b> can be formed to mount onto the needle assembly <b>14</b> after use to cover the proximal end <b>42</b> of the needle cannula. Alternatively, the locked needle assembly <b>14</b> in an extended position can be disposed of with the pen body <b>12</b>, if, for example, the needle assembly <b>14</b> is non-removably affixed to the pen body <b>12</b>.

p-0028To facilitate threaded removal and mounting of the needle assembly <b>14</b> relative to the pen body <b>12</b>, complementary ribs and grooves may be provided to extend longitudinally along the hub <b>24</b> and the shield <b>26</b> to prevent relative rotation therebetween as disclosed in U.S. Published patent application Ser. No. 2002/0133122 A1. By preventing relative rotation between the hub <b>24</b> and the shield <b>26</b>, the shield <b>26</b> can be easily grasped in mounting or dismounting the needle assembly <b>14</b> from the pen body <b>12</b>. If no rotational fixing is provided, the hub <b>24</b> has to be grasped in mounting or dismounting the needle assembly <b>14</b>.

p-0029While the invention has been described in relation to the preferred embodiments with several examples, it will be understood by those skilled in the art that various changes may be made without deviating from the spirit and scope of the invention as defined in the appended claims.